You didn't mention your viewing distance. They're both decent enough looking sets. The Vizio is indeed LED-backlit, apparently with some rudimentary type of local dimming (which, according to CNet, doesn't work), but it's smaller. I am pretty sure they're both actually 60hz TVs with some type of backlight scanning. LG is known for doing this, and the Vizio lists a "120Hz effective refresh rate. The Vizio should offer better backlight uniformity, but I have seen both and can't really discern a major difference between the two. I would go for the LG -- the TV will tend to shrink a bit after you get it, so it's always good to buy as big as you can afford. Take the $70 you save and put it towards a Blu-Ray player/streaming box or something for decent sound (they both sound pretty abysmal).
ht Panasonic 60" ZT60, Monitor Audio: Silver RX6, RX Centre, Radius 90HD; Martinlogan Dynamo 700, Marantz SR5006, PS3, Oppo BDP-103D
2ch Sony KDL-32W650A, Sony BDP-S1000ES, Marantz PM8004, JVC T-X3 tuner, Monitor Audio Silver RX1, REL T3, Apple TV, Peachtree Audio DAC•iT, Sennheiser HD598
lr Panasonic 50" ST60, Sony BDP-S5100, Apple TV
pc Energy CB-5, Audioengine D1, FiiO A1